Open3D ERROR ComputeHalfEdges failed. Duplicated half-edges

Question

Does anyone know how I can process a triangle mesh to allow conversion into a HalfEdgeTriangleMesh. I am trying to use the get_boundaries in HalfEdge to detect edges, which is not an included function in TriangleMesh

The last line gives the error.

mesh = mesh.remove_duplicated_triangles()
mesh = mesh.remove_degenerate_triangles()
mesh = mesh.remove_duplicated_vertices()
mesh = mesh.remove_non_manifold_edges()
mesh = mesh.remove_unreferenced_vertices()
half_edge_mesh = o3d.geometry.HalfEdgeTriangleMesh.create_from_triangle_mesh(mesh)

Have you perhaps found a way around this? I'm facing the same issue, and none of the open3d built-in methods seem to help — Teo Cherici, Apr 24 '20 at 10:33
Thank you for your reply. Do you mean that you got better results by using `get_non_manifold_edges` and then manually removing them from the object? — Teo Cherici, Apr 28 '20 at 08:35
I'm trying to generate a HalfEdgeTriangleMesh from a TriangleMesh, so that I can extract the boundary edges. Unfortunately, some of my meshes seem to have irregularities and non-manifold edges that cause the conversion to fail. — Teo Cherici, May 04 '20 at 08:58
So I just kept it as a triangle mesh and ran get_non_manifold_edges setting allow_boundary_edges to false — Alberto MQ, May 04 '20 at 14:42

xiterson · Accepted Answer · 2020-12-18T06:02:32.173

In Open3d,if you want to create HalfEdge from triangle mesh,please make sure your mesh is manifold and without singular vertex.In the case of a vertex has more than one output halfedge,runtime error will occur.In the newest version of Open3d,this bug has not been repaired.Open3d Link

    for (size_t triangle_index = 0;
     triangle_index < mesh_cpy->triangles_.size(); triangle_index++) {
    const Eigen::Vector3i &triangle = mesh_cpy->triangles_[triangle_index];
    size_t num_half_edges = het_mesh->half_edges_.size();

    size_t he_0_index = num_half_edges;
    size_t he_1_index = num_half_edges + 1;
    size_t he_2_index = num_half_edges + 2;
    HalfEdge he_0(Eigen::Vector2i(triangle(0), triangle(1)),
                  int(triangle_index), int(he_1_index), -1);
    HalfEdge he_1(Eigen::Vector2i(triangle(1), triangle(2)),
                  int(triangle_index), int(he_2_index), -1);
    HalfEdge he_2(Eigen::Vector2i(triangle(2), triangle(0)),
                  int(triangle_index), int(he_0_index), -1);

    if (vertex_indices_to_half_edge_index.find(he_0.vertex_indices_) !=
                vertex_indices_to_half_edge_index.end() ||
        vertex_indices_to_half_edge_index.find(he_1.vertex_indices_) !=
                vertex_indices_to_half_edge_index.end() ||
        vertex_indices_to_half_edge_index.find(he_2.vertex_indices_) !=
                vertex_indices_to_half_edge_index.end()) {
        utility::LogError(
                "ComputeHalfEdges failed. Duplicated half-edges.");//Throw a runtime error.
    }

    het_mesh->half_edges_.push_back(he_0);
    het_mesh->half_edges_.push_back(he_1);
    het_mesh->half_edges_.push_back(he_2);
    vertex_indices_to_half_edge_index[he_0.vertex_indices_] = he_0_index;
    vertex_indices_to_half_edge_index[he_1.vertex_indices_] = he_1_index;
    vertex_indices_to_half_edge_index[he_2.vertex_indices_] = he_2_index;
}

singular vertices just like red arrows vertices.In these vertices,error will occur. If you want to find boundary,please try Openmesh or Libigl.Both Openmesh and Libigl have python version.

Open3D ERROR ComputeHalfEdges failed. Duplicated half-edges

1 Answers1